Im thinking Instagram combined with reddit type app. Right now the Steemit website hopes to capture an audience similar to reddit users, but I think the real money is with users who use instagram. Instagram users who have 50k-100k followers advertise on their stories, "$50 all day promo", "$60 all day promo" etc. These are users who would definitely be interested in making money off of social media. They also know how to get followers and how to get people watching their content, whether it be belly-dancing videos, or butt pictures. Just think of how many butt models steemit could get if they made a mobile app. Butt models by nature would be super interested in making money off of social media, but they don't like to use computers, mainly because you can't take selfies on them, or butt pictures.
TLDR; somebody please tell me Steemit has plans to make a mobile app.